1. Field of the Invention
The present invention relates to heat exchangers and, more particularly, to vertical tube heat exchangers for use with fluidized solid particulates as a heat transfer medium The vertical tube heat exchanger of the present invention is especially well adapted for use in fluidized bed type steam and generating systems wherein fluidized solids are circulated as a heat transfer medium.
2. Background of the Prior Art
The following U.S. patents disclose steam generating systems and heat exchangers using fluidized bed solids as a heat transfer medium: Nicholson U.S. Pat. No. 2,697,653; Ostendorf U.S. Pat. No. 4,313,398; Campanile et al. U.S. Pat. No. 4,340,400; Klaren U.S. Pat. No. 4,427,053; Strohmeyer, Jr. U.S. Pat. No. 4,454,838; Komakine U.S. Pat. No. 4,499,944; Johnson U.S. Pat. No. 4,539,939; Klaren U.S. Pat. No. 4,567,940 and Brannstrom et al. U.S. Pat. No. 4,655,147.
One of the problems associated with fluidized bed heat exchange devices and systems, stems from the fact that fluidizing air must be introduced into a fluidized bed of solids from a lower or floor level and the temperature differentials between the floor material and the relatively cooler, fluid-filled tubes causes relative motion which must be accommodated without leakage of the solids into the plenum chamber or gas supply duct beneath the floor.